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Carmen Sarcinelli, Gabriella Fiorentino, Elio Pizzo, Simonetta Bartolucci, Danila Limauro
Peroxiredoxins (Prxs) are ubiquitous thiol peroxidases that are involved in the reduction of peroxides. It has been reported that prokaryotic Prxs generally show greater structural robustness than their eukaryotic counterparts, making them less prone to inactivation by overoxidation. This difference has inspired the search for new antioxidants from prokaryotic sources that can be used as possible therapeutic biodrugs. Bacterioferritin comigratory proteins (Bcps) of the hyperthermophilic archaeon Sulfolobus solfataricus that belong to the Prx family have recently been characterized...
2016: Archaea: An International Microbiological Journal
Keehong Lee, Melissa Kreider, Wubin Bai, Li-Chen Cheng, Saman Safari Dinachali, Kun-Hua Tu, Tao Huang, K Ntetsikas, G Liontos, A Avgeropoulos, C A Ross
The response of polystyrene-block-poly(dimethylsiloxane) (PS-b-PDMS) thin films to UV exposure during solvent vapor annealing is described, in order to improve their applicability in nanolithography and nanofabrication. Two BCPs were examined, one with the PS block as majority (f PS = 68%, M n = 53 kg mol(-1)), the other with PDMS block as majority (f PDMS = 67%, M n = 44 kg mol(-1)). A 5 min UV irradiation was applied during solvent vapor annealing which led to both partial crosslinking of the polymer and a small increase in the temperature of the annealing chamber...
October 13, 2016: Nanotechnology
Lu Wang, Hongji Liu, Fanzhu Li, Jianxiang Shen, Zijian Zheng, Yangyang Gao, Jun Liu, Youping Wu, Liqun Zhang
Although numerous research studies have been focused on studying the self-assembled morphologies of block-copolymers (BCPs) and their nanocomposites, little attention has been directed to explore the relation between their ordered structures and the resulting mechanical properties. We adopt coarse-grained molecular dynamics simulation to study the influence of the morphologies on the stress-strain behavior of pure block copolymers and block copolymers filled with uniform or Janus nanoparticles (NPs). At first, we examine the effect of the arrangement (di-block, tri-block, alternating-block) and the components of the pure block copolymers, and by varying the component ratio between A and B blocks, spherical, cylindrical and lamellar phases are all formed, showing that spherical domains bring the largest reinforcing effect...
October 5, 2016: Physical Chemistry Chemical Physics: PCCP
Ankit Vora, Kristin Schmidt, Gabriela Alva, Noel Arellano, Teddie P Magbitang, Anindarupa Chunder, Leslie Thompson, Elizabeth Lofano, Jed W Pitera, Joy Y Cheng, Daniel P Sanders
Orientation control of thin film nanostructures derived from block copolymers (BCPs) are of great interest for various emerging technologies like separation membranes, nanopatterning, and energy storage. While many BCP compositions have been developed for these applications, perpendicular orientation of these BCPs domains is still very challenging to achieve. Herein we report on a new, integration-friendly approach in which small amounts of a phase-preferential, surface active polymer (SAP) was used as an additive to a polycarbonate-containing BCP formulation to obtain perpendicularly oriented domains with 19 nm natural periodicity upon thermal annealing...
October 4, 2016: ACS Applied Materials & Interfaces
Tianlv Xu, James Farrell, Yuning Xu, Roya Momen, Steven R Kirk, Samantha Jenkins, David J Wales
Using the quantum theory of atoms in molecules a near complete combined directed spanning quantum topology phase diagram (QTPD) was constructed from the nine (H2 O)5 reaction-pathways and five unique Poincaré-Hopf solutions that were found after an extensive search of the MP2 potential energy surface. Two new energy minima that were predicted from earlier work are found and include the first (H2 O)5 conformer with a 3-DQT quantum topology. The stress tensor Poincaré-Hopf relation indicated a preference for 2-DQT (H2 O)5 topologies as well as the presence of coupling between shared-shell OH BCPs to the hydrogen-bond BCPs that share an H NCP...
December 5, 2016: Journal of Computational Chemistry
Yong-Hee Park, Da-Hye Yoo, Eun-Hee Kim, In-Kyung Song, Ji-Hyun Lee, Hee-Soo Kim, Woong-Han Kim, Jin-Tae Kim
This study aimed to investigate the optimal transducer level for accurate measurement of atrial and pulmonary arterial pressures in the supine position for patients with functional single ventricle. Contrast-enhanced chest computed tomographic images of 108 patients who underwent either the bidirectional cavopulmonary shunt (BCPS) placement or the Fontan procedure were reviewed. Vertical distances from the skin of the back to the uppermost levels of fluid in the single atrium or the pulmonary artery confluence and their ratios to the greatest anteroposterior (AP) diameter of the thoracic cage were determined...
October 1, 2016: Pediatric Cardiology
Itay Wiser, Eliezer Avinoah, Oren Ziv, Adam J Parnass, Roni Averbuch Sagie, Lior Heller, Tali Friedman
BACKGROUND: Laparoscopic adjustable gastric banding (LAGB) surgery is the safest yet least effective method for massive weight loss. Thirty to 50 percent of patients undergoing LAGB will regain part of their lost weight. OBJECTIVE: To evaluate the effect of body contouring plastic surgery (BCPS) following LAGB on long-term body mass index (BMI) control. SETTING: Department of Surgery A, Soroka University Medical Center, Beer-Sheva, Israel...
September 7, 2016: Journal of Plastic, Reconstructive & Aesthetic Surgery: JPRAS
Lynn Groß, Carmen Herrmann
We present an approach for calculating local electric dipole moments for fragments of molecular or supramolecular systems. This is important for understanding chemical gating and solvent effects in nanoelectronics, atomic force microscopy, and intensities in infrared spectroscopy. Owing to the nonzero partial charge of most fragments, "naively" defined local dipole moments are origin-dependent. Inspired by previous work based on Bader's atoms-in-molecules (AIM) partitioning, we derive a definition of fragment dipole moments which achieves origin-independence by relying on internal reference points...
September 30, 2016: Journal of Computational Chemistry
Xiaoyu Li, Bixin Jin, Yang Gao, Dominic W Hayward, Mitchell A Winnik, Yunjun Luo, Ian Manners
Precise control over the morphology and dimensions of block copolymer (BCP) micelles has attracted interest due to the potential of this approach to generate functional nanostructures. Incorporation of liquid crystalline (LC) block can provide additional ways to vary micellar morphologies, but the formation of uniform micelles with controllable dimensions from LC BCPs has not yet been realized. Herein, we report the preparation of monodisperse cylindrical micelles with a LC poly(2-(perfluorooctyl)ethyl methacrylate (PFMA) core via a fragmentation-thermal annealing (F-TA) process, resembling the "self-seeding" process of crystalline BCP micelles...
September 12, 2016: Angewandte Chemie
Dan Zhao, Matteo Di Nicola, Mohammad M Khani, Jacques Jestin, Brian C Benicewicz, Sanat K Kumar
We compare the self-assembly of silica nanoparticles (NPs) with physically adsorbed polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) copolymers (BCP) against NPs with grafted bimodal (BM) brushes comprised of long, sparsely grafted PS chains and a short dense carpet of P2VP chains. As with grafted NPs, the dispersion state of the BCP NPs can be facilely tuned in PS matrices by varying the PS coverage on the NP surface or by changes in the ratio of the PS graft to matrix chain lengths. Surprisingly, the BCP NPs are remarkably better dispersed than the NPs tethered with bimodal brushes at comparable PS grafting densities...
September 14, 2016: Soft Matter
Yufeng Wang, Mingjiang Zhong, Jiwon V Park, Aleksandr V Zhukhovitskiy, Weichao Shi, Jeremiah A Johnson
We report a stepwise assembly strategy for the integration of metal-organic cages (MOCs) into block copolymers (BCPs). This approach creates "block co-polyMOC" (BCPMOC) materials whose microscopic structures and mechanical properties are readily tunable by adjusting the size and geometry of the MOCs and the composition of the BCPs. In the first assembly step, BCPs functionalized with a pyridyl ligand on the chain end form star-shaped polymers triggered by metal-coordination-induced MOC assembly. The type of MOC junction employed precisely determines the number of arms for the star polymer...
August 24, 2016: Journal of the American Chemical Society
Sang-Kon Kim
For future semiconductor device scaling, self-assembly, directed self-assembly (DSA) of block copolymers (BCPs), is a promising method with simplified processing conditions; however, critical challenge is defect control for fine pattern. Electric field is a method for the defect control. In this paper, for electric field effects to jog defects, the electric field induced self-assembled patterns is modeled and simulated by using the Monte Carlo method of dielectric polymers, the self-consistent-field theory (SCFT), and the Navier-Stokes equation...
March 2016: Journal of Nanoscience and Nanotechnology
Joshua S Silverstein, Brendan J Casey, Peter Kofinas, Benita J Dair
Understanding the interactions of biomacromolecules with nanoengineered surfaces is vital for assessing material biocompatibility. This study focuses on the dynamics of protein adsorption on nanopatterned block copolymers (BCPs). Poly(styrene)-block-poly(1,2-butadiene) BCPs functionalized with an acid, amine, amide, or captopril moieties were processed to produce nanopatterned films. These films were characterized using water contact angle measurements and atomic force microscopy in air and liquid to determine how the modification process affected...
February 2016: Journal of Nanoscience and Nanotechnology
Lynn Groß, Carmen Herrmann
Local dipole moments (i.e., dipole moments of atomic or molecular subsystems) are essential for understanding various phenomena in nanoscience, such as solvent effects on the conductance of single molecules in break junctions or the interaction between the tip and the adsorbate in atomic force microscopy. We introduce GenLocDip, a program for calculating and visualizing local dipole moments of molecular subsystems. GenLocDip currently uses the Atoms-In-Molecules (AIM) partitioning scheme and is interfaced to various AIM programs...
September 30, 2016: Journal of Computational Chemistry
Yivan Jiang, Matthew R Golder, Hung V-T Nguyen, Yufeng Wang, Mingjiang Zhong, Jonathan C Barnes, Deborah J C Ehrlich, Jeremiah A Johnson
Studies on the phase segregation of unimolecular block copolymers (BCPs) are limited by a lack of reliable, versatile methods for the synthesis of such polymers on the preparative scale. Herein, we describe an advancement of Iterative Exponential Growth (IEG) wherein chiral allyl-based IEG oligomers are subjected to thiol-ene reactions and converted into unimolecular BCPs. With this strategy we have synthesized uniform BCPs with molar masses up to 12.1 kDa on ∼1 g scale. BCPs composed of decane-based side chains and either triethyleneglycol- or thioglycerol-based side chains phase-segregate into hexagonal cylinder morphologies...
August 3, 2016: Journal of the American Chemical Society
Yong Wang
Pores regulate the entry and exit of substances based on the differences in physical sizes or chemical affinities. Pore uniformity, ordering, and the homogeneity of the surface chemistry of the pore walls are vital for maximizing the performance of a porous material because any scattering in these parameters weakens the capability of pores to discriminate foreign substances. Most strategies for the creation of homogeneous pores are destructive, and sacrificial components in the precursor materials must be selectively removed to generate porosities...
July 19, 2016: Accounts of Chemical Research
Rajashekharayya A Sanguramath, Paul F Nealey, Roy Shenhar
Quasi-block copolymers (q-BCPs) are block copolymers consisting of conventional and supramolecular blocks, in which the conventional block is end-terminated by a functionality that interacts with the supramolecular monomer (a "chain stopper" functionality). A new design of q-BCPs based on a general polymeric chain stopper, which consists of polystyrene end-terminated with a sulfonate group (PS-SO3 Li), is described. Through viscosity measurements and a detailed diffusion-ordered NMR spectroscopy study, it is shown that PS-SO3 Li can effectively cap two types of model supramolecular monomers to form q-BCPs in solution...
July 11, 2016: Chemistry: a European Journal
Myung-Seok Seo, Inyoung Jeong, Joon-Suh Park, Jinwoo Lee, Il Ki Han, Wan In Lee, Hae Jung Son, Byeong-Hyeok Sohn, Min Jae Ko
We fabricated perovskite solar cells with enhanced device efficiency based on vertically oriented TiO2 nanostructures using a nanoporous template of block copolymers (BCPs). The dimension and shape controllability of the nanopores of the BCP template allowed for the construction of one-dimensional (1-D) TiO2 nanorods and two-dimensional (2-D) TiO2 nanowalls. The TiO2 nanorod-based perovskite solar cells showed a more efficient charge separation and a lower charge recombination, leading to better performance compared to TiO2 nanowall-based solar cells...
June 2, 2016: Nanoscale
Kang Hee Ku, Jae Man Shin, Daniel Klinger, Se Gyu Jang, Ryan C Hayward, Craig J Hawker, Bumjoon J Kim
A series of porous block copolymer (BCP) particles with controllable morphology and pore sizes was fabricated by tuning the interfacial behavior of BCP droplets in oil-in-water emulsions. A synergistic adsorption of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) BCPs and sodium dodecyl sulfate (SDS) to the surface of the emulsion droplet induced a dramatic decrease in the interfacial tension and generated interfacial instability at the particle surface. In particular, the SDS concentration and the P4VP volume fraction of PS-b-P4VP were key parameters in determining the degree of interfacial instability, leading to different types of particles including micelles, capsules, closed-porosity particles, and open-porosity particles with tunable pore sizes ranging from 10 to 500 nm...
May 24, 2016: ACS Nano
Yuji Sugibayashi, Satoko Hayashi, Waro Nakanishi
The nature of halogen bonds of the Y-X-✶-π(C6 H6 ) type (X, Y=F, Cl, Br, and I) have been elucidated by using the quantum theory of atoms in molecules (QTAIM) dual-functional analysis (QTAIM-DFA), which we proposed recently. Asterisks (✶) emphasize the presence of bond-critical points (BCPs) in the interactions in question. Total electron energy densities, Hb (rc ), are plotted versus Hb (rc )-Vb (rc )/2 [=(ħ(2) /8m)∇(2) ρb (rc )] for the interactions in QTAIM-DFA, in which Vb (rc ) are potential energy densities at the BCPs...
August 18, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
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